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powerpc/bpf: BPF JIT compiler for 64-bit Little Endian

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This enables the Berkeley Packet Filter JIT compiler
for the PowerPC running in 64bit Little Endian.

Signed-off-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Philippe Bergheaud 2013-09-24 14:13:35 +02:00 committed by Benjamin Herrenschmidt
parent 711b5138d5
commit 9c662cad2f
4 changed files with 21 additions and 16 deletions
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1
arch/powerpc/include/asm/ppc-opcode.h
View file

@ -203,6 +203,7 @@
/* Misc instructions for BPF compiler */
#define PPC_INST_LD 0xe8000000
#define PPC_INST_LHZ 0xa0000000
#define PPC_INST_LHBRX 0x7c00062c
#define PPC_INST_LWZ 0x80000000
#define PPC_INST_STD 0xf8000000
#define PPC_INST_STDU 0xf8000001

10
arch/powerpc/net/bpf_jit.h
View file

@ -92,6 +92,8 @@ DECLARE_LOAD_FUNC(sk_load_byte_msh);
___PPC_RA(base) | IMM_L(i))
#define PPC_LHZ(r, base, i) EMIT(PPC_INST_LHZ | ___PPC_RT(r) | \
___PPC_RA(base) | IMM_L(i))
#define PPC_LHBRX(r, base, b) EMIT(PPC_INST_LHBRX | ___PPC_RT(r) | \
___PPC_RA(base) | ___PPC_RB(b))
/* Convenience helpers for the above with 'far' offsets: */
#define PPC_LD_OFFS(r, base, i) do { if ((i) < 32768) PPC_LD(r, base, i); \
else { PPC_ADDIS(r, base, IMM_HA(i)); \
@ -186,6 +188,14 @@ DECLARE_LOAD_FUNC(sk_load_byte_msh);
PPC_ORI(d, d, (uintptr_t)(i) & 0xffff); \
} } while (0);
#define PPC_LHBRX_OFFS(r, base, i) \
do { PPC_LI32(r, i); PPC_LHBRX(r, r, base); } while(0)
#ifdef __LITTLE_ENDIAN__
#define PPC_NTOHS_OFFS(r, base, i) PPC_LHBRX_OFFS(r, base, i)
#else
#define PPC_NTOHS_OFFS(r, base, i) PPC_LHZ_OFFS(r, base, i)
#endif
static inline bool is_nearbranch(int offset)
{
return (offset < 32768) && (offset >= -32768);

9
arch/powerpc/net/bpf_jit_64.S
View file

@ -43,8 +43,11 @@ sk_load_word_positive_offset:
cmpd r_scratch1, r_addr
blt bpf_slow_path_word
/* Nope, just hitting the header. cr0 here is eq or gt! */
#ifdef __LITTLE_ENDIAN__
lwbrx r_A, r_D, r_addr
#else
lwzx r_A, r_D, r_addr
/* When big endian we don't need to byteswap. */
#endif
blr /* Return success, cr0 != LT */
.globl sk_load_half
@ -56,7 +59,11 @@ sk_load_half_positive_offset:
subi r_scratch1, r_HL, 2
cmpd r_scratch1, r_addr
blt bpf_slow_path_half
#ifdef __LITTLE_ENDIAN__
lhbrx r_A, r_D, r_addr
#else
lhzx r_A, r_D, r_addr
#endif
blr
.globl sk_load_byte

17
arch/powerpc/net/bpf_jit_comp.c
View file

@ -17,14 +17,8 @@
#include "bpf_jit.h"
#ifndef __BIG_ENDIAN
/* There are endianness assumptions herein. */
#error "Little-endian PPC not supported in BPF compiler"
#endif
int bpf_jit_enable __read_mostly;
static inline void bpf_flush_icache(void *start, void *end)
{
smp_wmb();
@ -346,18 +340,11 @@ static int bpf_jit_build_body(struct sk_filter *fp, u32 *image,
break;
/*** Ancillary info loads ***/
/* None of the BPF_S_ANC* codes appear to be passed by
* sk_chk_filter(). The interpreter and the x86 BPF
* compiler implement them so we do too -- they may be
* planted in future.
*/
case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
protocol) != 2);
PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
protocol));
/* ntohs is a NOP with BE loads. */
PPC_NTOHS_OFFS(r_A, r_skb, offsetof(struct sk_buff,
protocol));
break;
case BPF_S_ANC_IFINDEX:
PPC_LD_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,